I loved the game but it always felt unfinished to me. A lot of the mechanics were cool, like Pred tree jumping, Alien wallcrawling, but they needed some refinement to make them less clunky. The rock, paper, scissors style of hand-to-hand combat was pretty good too, imo. But again, probably could've used some refinement.
There were other neat things implemented, too, like Aliens hiding in the walls of the hive and the Pred's vocal mimicry. Unfortunately they weren't fully realised yet, but the potential for future possibilities was there. Shame we never got a follow up where they took these ideas further.
Also, I loved the execution kills. These could be problematic in multiplayer, but in single player they were glorious.
The whole game for me is just a list of pros and cons. It felt like they only barely touched on what was possible with the AvP formula.